Regulated power sources

ABSTRACT

Disclosed herein are regulated power supplies. The power source delivers power to a system load and includes battery units. The power source also includes power flow devices coupled to the battery units that are configured to provide power from the battery units to the system load. Each power flow device corresponds to a respective one of the battery units, and includes a one direction current flow device connected in series with a current regulator between the respective battery unit and the system load.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.17/346,377 filed on Jun. 14, 2021, which is a Continuation of U.S.application Ser. No. 16/446,781 filed on Jun. 20, 2019, now U.S. Pat.No. 11,050,280, which claims priority to U.S. Provisional ApplicationSer. No. 62/691,370, filed on Jun. 28, 2018, the contents of all ofwhich are incorporated fully herein by reference.

TECHNICAL FIELD

The subject matter disclosed herein generally relates to a power sourcefor regulating power supplied to a system load and uses of the same.

BACKGROUND OF THE INVENTION

Power sources with additional capacity are needed to address theever-increasing energy requirements of electronic components. Such powersources typically include multiple batteries, which require regulationfor safe and efficient discharge.

BRIEF DESCRIPTION OF THE FIGURES

The invention is best understood from the following detailed descriptionwhen read in connection with the accompanying drawings, with likeelements having the same reference numerals. When a plurality of similarelements are present, a single reference numeral may be assigned to theplurality of similar elements with a small letter designation referringto specific elements. When referring to the elements collectively or toa non-specific one or more of the elements, the small letter designationmay be dropped. This emphasizes that according to common practice, thevarious features of the drawings are not drawn to scale unless otherwiseindicated. On the contrary, the dimensions of the various features maybe expanded or reduced for clarity. Included in the drawings are thefollowing figures:

FIG. 1A is a high level block diagram of example electronic componentsof a power source for delivering power to a system load.

FIG. 1B is a block diagram of an example operation of the power sourceof FIG. 1A.

FIG. 2A is a perspective view of example eyewear including electroniccomponents of a power source and a support structure supporting theelectronic components.

FIG. 2B is an illustration of a power source installed on a frame of theeyewear of FIG. 2A.

FIG. 3 is a block diagram of an example of the electronic componentssupported by the eyewear of FIG. 2A.

FIG. 4 is a flowchart showing an example of a power source regulationmethod for supplying power to a system load when a power source isconnected to the system load.

FIG. 5 is a flowchart showing another example of a power sourceregulation method for supplying power to a system load when a powersource is connected to the system load.

FIG. 6 is a flowchart showing another example of a power sourceregulation method for supplying power to a system load when a powersource is connected to the system load.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth by way of examples in order to provide a thorough understanding ofthe relevant teachings. However, it should be apparent to those skilledin the art that the present teachings may be practiced without suchdetails. In other instances, well known methods, procedures, components,and circuitry have been described at a relatively high-level, withoutdetail, in order to avoid unnecessarily obscuring aspects of the presentteachings.

The term “coupled” as used herein refers to any logical, optical,physical or electrical connection, link or the like. Unless describedotherwise, coupled elements or devices are not necessarily directlyconnected to one another and may be separated by intermediate componentsor elements.

FIG. 1A depicts a high-level block diagram of example electroniccomponents of a power source 100 coupled to a system load 140, acharging port 150, and a controller 160. The power source 100 isconfigured to supply power to the system load 140. The system load maybe essentially any device that consumes power. Some examples of thesystem load includes a system processor, image processor, display,sensor etc. As shown, the power source 100 includes a plurality ofbattery units 102 a-102 n connected in parallel with each other. Each ofthe plurality of battery units 102 is coupled to the system load 140.Each of the plurality of battery units 102 draws current and thus hasits own rated current, which may be the same or different as otherbattery units 102. In one example, the controller 160 is configured todynamically control the battery units 102 to maintain the rated currentof each battery unit in order to maximize the energy extraction asdiscussed in detail below.

In one example, each battery unit 102 includes an ideal diode 104 (e.g.,a one direction current flow device with very low forward voltage dropand reverse current leakage), a current limiting load switch 106, and acharger 108. The controller 160 is coupled to the current limiting loadswitch 106 to control the maximum amount that flows from the respectivebattery unit 102. The ideal diode 104 is connected in series with thecurrent limiting load switch 106 to prevent current from flowing betweenthe battery units 102.

The current limiting load switch 106 of each battery unit 102 isconfigured to limit the current flowing through that current limitingload switch 106 to a set current limit, which can be individual adjustedfor each respective battery unit 102. In one example, the controller 160functions to dynamically adjust the respective current limit of thecurrent limiting load switch 106 to prevent the respective battery unit102 from exceeding its respective rated current, which may be used toeven discharge the battery units 102 in order to maximize energyextraction.

The illustrated current limiting load switch 106 includes a currentsensing amplifier 105 and a current controller 107. The current sensingamplifier 105 functions to determine current flow from the respectivebattery unit 102 (e.g., by measuring a voltage, v, across a resistance,r, having a known value, and computing the current, i=v/r). The currentcontroller 107 adjusts the respective current limit (e.g., using a metaloxide semiconductor field effect transistor; MOSFET) with input from thecurrent sensing amplifier 105 and under control of the controller 160 tomaintain the current flow of the respective battery unit 102 fromexceeding the set current limit.

In one example, each battery unit 102 includes a respective charger 108and all chargers 108 are connected to a common charging port 150. Inaccordance with this example, the charger 108 of a respective batteryunit 102 is configured control the current flow into that battery unit102.

Although the example of FIG. 1A illustrates each of the ideal diode 106,the current limiting load switch 106, and the charger 108 positionedwithin their respective battery units 102 a-102 n, in another example,the ideal diode 104, the charger current limiting load switch 106 and/orthe charger 108 may be positioned outside their respective battery units102 a-102 n (e.g., in an integrated circuit (IC)).

As shown in FIG. 1A, the battery units 102 may also include a Schottkycircuit 110 (e.g., a Schottky diode coupled in parallel with the idealdiode 104 and the current limiting load switch 106). The controller 160may selectively enable/disable the ideal diode 104, the current limitingload switch 106, and the Schottky circuit 110. In one example, thecontroller 160 enables the ideal diode 104 and current limiting loadswitch 106 and disables the Schottky circuit during a normal/activeoperation mode (i.e., first mode of operation) and the controller 160disables the ideal diode 104 and current limiting load switch 106 andenables the Schottky circuit 110 during a low power operation mode(e.g., sleep/off power operation mode; i.e., second mode of operation).As Schottky diodes have a higher forward voltage drop and a lowerleakage current, the Schottky circuit is useful in minimizing standbycurrent consumption of the battery unit.

FIG. 1B depicts a block diagram illustrating an example operation of thepower source 100 of FIG. 1A. The power source 100 includes a pluralityof power flow devices 170 a-170 n, each of which are coupled to itscorresponding battery units 102. Each of the power flow devices 170provide power from the corresponding battery unit 102 to the system load140 when the corresponding battery unit is connected to the system load140. As shown, each of the power flow devices 170 a-170 n includes aone-direction current flow device 172 a-172 n (e.g., ideal diode 104 ofFIG. 1A) and a current regulator 174 a-174 n (e.g., current limitingload switch 106 of FIG. 1A). Each of the one direction current flowdevices 172 functions to prevent the flow of current between each of itsrespective battery units 102. Each of the current regulators 174functions to regulate the current flowing from its respective batteryunits 102 a-102 n to the system load 140. Each of the one directioncurrent flow devices 172 a-172 n is connected in series with thecorresponding current regulator 174 a-174 n between the respectivebattery unit 102 a-102 n and the system load 140.

The illustrated power source 100 includes a plurality of battery statedetermining devices 180 a-180 n coupled to the respective battery units102 and the controller 160. Each of the plurality of battery statedetermining devices 180 determines a current state of charge of therespective battery units 102. The battery-determining device 180 of eachbattery unit 102 sends the respective current state of charge to thecontroller 160. In one example, controller 160 is configured to adjustthe current limit in the each of the respective power flow devices 170based on a state of the charge of the respective battery units 102.

In one example, assuming two battery units, the battery statedetermining device 180 a sends a current state of charge of the batteryunit 102 a to the controller 160 and the battery state-determiningdevice 180 b sends the current state of charge of the battery unit 102 bto the controller 160. If the current state of charge for the batteryunit 102 a is at a level lower (e.g., percentage capacity wise) than thecurrent state of charge for the battery unit 102 b, the controller 160may decrease the set current limit of the first battery unit 102 a,which results in the first battery unit discharging at a slower rate.For example, if the system load 140 requires 800 mA and each of thebattery units 102 a and 102 b is set with an initial current limit valueof 400 mA to run the system load 140. In one scenario, if it isdetermined that the current state of charge of the battery unit 102 b is50% and the current state of charge of the battery unit 102 a is 80%.The controller 160 may decrease the current limit of battery unit 102 bto 200 mA and increase the current limit of battery unit 102 a to 600 mAin order to even out the discharge level of the two battery units 102 aand 102 b.

Each of the power flow devices 172 a-172 n includes the Schottky circuit110 a-110 n described above.

A system voltage detector 190 is coupled to the system load 140 and isconfigured to detect a system voltage level of the system load 140. Inone example, the controller 160 is coupled to the system voltagedetector 190 to receive/detect the system voltage level. If thecontroller 160 determines that the system voltage level of the systemload 140 is below a threshold voltage level (e.g., a minimum voltagerequired to activate or maintain activation in the system load 140), thecontroller 160 may function to briefly increase current output (e.g., toa maximum amount) from each of the plurality of battery units 102 a-102n connected to the system load 140. Specifically, the controller 160functions to enable each of the current regulators 174 a-174 n toincrease the current limit. In one example, the current limit isincreased for a very short period of time (e.g., 20 milliseconds) untilthe system load is either activated or is maintained for activation.

FIG. 2A depicts a perspective view of example eyewear 200 includingcomponents of the power source 100 (FIG. 1A). The illustrated eyewear200 includes a support structure 213 that has temples 214 a and 214 band a frame 216. The frame 216 is transparent for illustration purposes.Support structure 213 is configured to support one or more opticalelements within a field of view of a user when worn by a user. Forexample, the frame 216 is configured to support the one or more opticalelement. As used herein, the term “optical elements” refers to lenses,transparent pieces of glass or plastic, projectors, screens, displaysand other devices for presenting visual images or through which visualimages may be perceived by a user.

The power source 100 functions to power the eyewear 200. Supportstructure 213 is configured to support the power source 100. The frame216 includes a first side 216 a and a second side 216 b. As illustrated,in one example, a first battery unit 102 a is positioned on the firstside 216 a and a second battery unit 102 b is positioned on the secondside 216 b. In one example, the eyewear 200 includes the charging port150 (not shown) coupled to each of the first and the second batteryunits 102 a and 102 b, respectively, via a flexible printed circuitboard (FPCB) 226A, B. In addition, eyewear 200 includes system load 140(not shown) installed at one or more locations throughout frame 216and/or temples 214 a and 214 b. The system load 140 may include a systemprocessor, an image processor, a display, and/or a sensor, and may becoupled to the first and the second battery units 102 a and 102 b,respectively, e.g., through one or more FPCBs.

The FPCB 226A and 226B as shown in FIG. 2A are embedded within the frame216. The FPCB 226 may include a power bus coupled to both the first andthe second battery units 102 a and 102 b. For example, as shown in FIG.2A, the FPCB 226 is routed throughout the frame 216 extending to boththe first and the second sides 216 a and 216 b to electrically connectthe first and the second battery units 102 a and 102 b together. TheFPCB 226 may include one or more electrical traces for routingelectrical signals between the first and the second battery units 102 aand 102 b.

FPCBs 226 are routed through various portions of frame 216 (andoptionally or alternatively the temples 214 a and 214 b) to electricallyconnect the first and the second battery units 102 a and 102 b together,to the system load 140, and to the power flow components. For example,as shown in FIG. 2A, FPCB 226A (primary FPCB) is routed through frame216 to electrically connect the first and the second battery units 102 aand 102 b together. Additionally, secondary FPCB 226B, C may extend fromthe main FPCB 226A to other components such as sensors (not shown)embedded into a nose pads 234A, 234B. In another example, a further FPCB226D extends from the main FPCB 226A to components embedded into thetemple 214 b. As such, the use of secondary FPCBs allow other electronicdevices to be embedded at various locations throughout the structure ofeyewear 200. These electronic devices are positioned to provide a way toregulate power from the power source 100 supplied to power the eyewear200.

FPCBs 226A, 226B, 226C and 226D include one or more electrical tracesfor routing electrical signals between the first and the second batteryunits 102 a and 102 b respectively and the other electronic devices.These FPCBs may be embedded in the frame and temples of eyewear 200during the manufacturing process.

For example, during a first shot of a two-shot molding process, plasticis injected into a mold to form the front half of frame 216 and/ortemple 214 a. After forming the front halves, the FPCBs, along with anyelectronic components are inserted and positioned within the mold atlocations with respect to the front halves. During a second shot of thetwo-shot molding process, more plastic is injected into the mold tocover the components and form the back half of frame 216 or temple 214 asuch that the FPCBs and electronics are embedded between the front andback halves of frame 216 and/or temple 214 a. After the frame and bothtemples are formed using the molding process, they are connectedtogether (e.g., fasteners such as screws and/or fastening materials suchas glue) to form the finished eyewear 200.

FIG. 2B illustrates a close up exploded view of a portion of the powersource 100 embedded into the frame 216 of the eyewear 200 of FIG. 2A. Inthe illustrated example, the second battery unit 102 b is housed in thesecond side 216 b of the frame 216 of the eyewear 200. As discussedabove, the second battery unit 102 b is associated with a second powerflow device 170 b configured to prevent current from flowing between thesecond battery unit 102 b and other respective battery units and toprevent the second battery unit 102 b from exceeding a set currentdischarge limit. In one example, the second power flow device 170 b isco-located with the second battery unit 102 b. In another example, oneor more components of the power flow device 170 b may be distinct andseparate from the second battery unit 102 b.

FIG. 3 is a block diagram of example electronic components of theeyewear 200 of FIG. 2A. The illustrated electronic components include acontroller 300 (e.g. system processor, image processor, etc.) forcontrolling the various devices in eyewear 200, wireless module (e.g.Bluetooth™) 302 for facilitating communication between eyewear 200 and aclient device (e.g. Smartphone), power source 100 for powering eyewear200, flash storage 306 for storing data (e.g., images, video, imageprocessing software, etc.), LEDs 308 (e.g. colored LEDs) for providinginformation to the user, button 310 for triggering eyewear 200 tocapture images/video, camera/microphone 312 for capturing images/videoand sound, and a physical activity sensor (e.g., accelerometer sensingmovement, button such as button 310 pressed by a user, switchincorporated into a hinge to detect when a respective temple is movedfrom a collapsed condition to a wearable condition, etc.).

Wireless module 302 may connect with a client device such as asmartphone, tablet, phablet, laptop computer, desktop computer,networked appliance, access point device, or any other such devicecapable of connecting with wireless module 302. These connections may beimplemented, for example, using any combination of Bluetooth, BluetoothLE, Wi-Fi, Wi-Fi direct, a cellular modem, and a near fieldcommunication system, as well as multiple instances of any of thesesystems. Communication may include transferring software updates,images, videos, sound between eyewear 200 and the client device (e.g.,images captured by eyewear 200 may be uploaded to a smartphone).

Camera/microphone 312 for capturing the images/video may include digitalcamera elements such as a charge-coupled device, a lens, or any otherlight capturing elements that may be used to capture image data.Camera/microphone 312 includes a microphone having a transducer forconverting sound into an electrical signal.

Button 310 may be a physical button that, when depressed, sends a userinput signal to controller 300. A press of button 310 for apredetermined period of time (e.g., three seconds) may be processed bycontroller 300 as a request to turn on eyewear 200 (e.g., transitioneyewear 200 from a second mode (e.g., an off or sleep mode of operation)to a first mode (e.g., normal or active mode of the operation). In oneexample, the controller 300 may send a command to the current controller107 of the respective battery unit 102 to switch from the first mode tothe second mode of the operation and vice versa.

Controller 300 is a controller that controls the electronic components.For example, controller 300 includes circuitry to receive signals fromcamera 312 and process those signals into a format suitable for storagein memory 306. Controller 300 is structured such that it may be poweredon and booted to operate in a normal operational mode, or to enter asleep mode. Depending on various power design elements controller 300may still consume a small amount of power even when it is in an offstate and/or a sleep state. This power will, however, be negligiblecompared to the power used by controller 300 when it is in an on or theactive state, and will also have a negligible impact on battery life.

In one example, controller 300 includes a microprocessor integratedcircuit (IC) customized for processing sensor data from camera 312,along with volatile memory used by the microprocessor to operate. Thememory may store software code for execution by controller 300. Forexample, the software code may instruct controller 300 to control themode of operation of the electronic components.

Each of the electronic components require power to operate. As describedabove, power source 100 that may include a battery (e.g. 102 a-102 n ofFIGS. 1A and 1B), power converter and distribution circuitry (e.g.,FPCBs). The battery units may include rechargeable batteries such aslithium-ion or the like. Power converter and distribution circuitry mayinclude electrical components for filtering and/or converting voltagesfor powering the various electronic components.

LEDs 308, among other uses, may be used as indicators on eyewear 200 toindicate a number of functions. For example, LEDs 308 may illuminateeach time the user presses button 310 to indicate that eyewear 200 isrecording images and/or video and/or sound.

The various connections between controller 300 and the other electroniccomponents including the sensors shown in FIG. 2A are accomplishedthrough wires, PCBs and FPCBs. These electrical connections are routedthrough various portions of frame 216 and/or temples 214 a and 214 bduring the manufacturing (e.g., two-shot molding) process. Once eyewear200 is manufactured, these electrical connections are fully embedded inthe eyewear and may or may not be visible to the user based on theopacity of the manufacturing material.

FIG. 4 is a flowchart 400 showing an example of a power sourceregulation method for supplying power to a system load when a powersource is connected to the system load. The steps of FIG. 4 will bedescribed with reference to the power source 100 depicted in anddescribed above with reference to FIG. 1B. Other suitable components forimplementing one or more of the steps of flowchart 400 will beunderstood by one of skill in the art from the description herein. Itwill be understood that one or more steps within flow chart 400 may beomitted and/or performed out of order without departing from the scopeof the present invention.

At step 402, set a respective current limit to a respective initialvalue for each of a plurality of battery units. In an example,controller 160 sets the current limit for each battery unit 102 byproviding a current limit value to a controller of a current regulator174 for each battery unit 102.

At step 404, monitor a state of charge of each of the plurality ofbattery units. In an example, controller 160 monitors the state ofcharge by receiving feedback from battery state determining devices 180a-180 n that monitor the state of charge of the respective batteryunits' 102 a-102 n.

At step 406, individually adjust the respective current limit of atleast two of the plurality of battery units based on the monitored stateof charge of each of the plurality of battery units. In an example,controller 160 individually adjusts the current limit of each of theplurality of battery units 102 a-102 n based on a state of chargereceived from the battery state determining devices 180 in step 404. Thecontroller 160 may adjust the current limit by setting the current limitfor each battery unit 102 by providing a revised current limit value toa controller of a current regulator 174. In an example, the controller160 reduces the current limit for battery units that have a relativelylow level of charge (e.g., 5% below that of a battery unit with thehigher level state of charge) and/or increase the current limit forbattery units that have a relatively high level of charge (e.g., 10%above that of a battery unit with the higher level state of charge). Inan example, the current limit decrease/increase is proportional to therelative state of charge.

Steps 404 and 406 may repeat periodically (e.g., once a minute) toensure that the battery units 102 are discharging evenly.

FIG. 5 is a flowchart 500 showing an example of a power sourceregulation method for supplying power to a system load when a powersource is connected to the system load. The steps of FIG. 5 will bedescribed with reference to the power source 100 depicted in anddescribed above with reference to FIG. 1B. Other suitable components forimplementing one or more of the steps of flowchart 500 will beunderstood by one of skill in the art from the description herein. Itwill be understood that one or more steps within flow chart 500 may beomitted and/or performed out of order without departing from the scopeof the present invention.

At step 502, set a respective current limit to a respective initialvalue for each of a plurality of battery units when connected to asystem load. In an example, controller 160 sets the current limit foreach battery unit 102 by providing a current limit value to a controllerof a current regulator 174 for each battery unit 102.

At step 504, monitor a system voltage level of the system load. In anexample, controller 160 receives feedback from the system voltagedetector 190 to monitor the system voltage level.

At block 506, determine that the system voltage level is below athreshold voltage level. In one example, controller 160 compares thesystem voltage received from the system voltage detector 190 to athreshold value (e.g., 3.0 volts) to determine if a “droop” voltagecondition is present.

At block 508, increase the respective current limit of at least two ofthe plurality of battery units among the plurality of battery unitsbased on the system voltage level falling below the threshold voltagelevel. In one example, the controller 160 increases the respectivecurrent limit of the at least two battery units to a maximum amount fora temporary period of time (e.g., 20 milliseconds).

Steps 504 through 506 may repeat, e.g., with a 100 millisecond restbetween maximum current delivery to avoid damage to the battery units102.

FIG. 6 is a flowchart 600 showing an example of a power sourceregulation method for supplying power to a system load when a powersource is connected to the system load. The steps of FIG. 6 will bedescribed with reference to the power source 100 depicted in anddescribed above with reference to FIG. 1B. Other suitable components forimplementing one or more of the steps of flowchart 600 will beunderstood by one of skill in the art from the description herein. Itwill be understood that one or more steps within flow chart 600 may beomitted and/or performed out of order without departing from the scopeof the present invention.

At step 602, set a respective current limit to a respective initialvalue for each of a plurality of battery units. In an example,controller 160 sets the current limit for each battery unit 102 byproviding a current limit value to a controller of a current regulator174 for each battery unit 102.

At step 604, determine whether the system load is in the first mode(e.g., high power mode, as in active/normal operation mode) or in thesecond mode (e.g., low power mode such as in sleep/off operation mode).In an example, controller 160 determines the mode of operation based ona signal from a device controller (e.g., controller 300 (FIG. 3 ) ofeyewear 200 (FIG. 2A).

At step 606, which is reached if the system load is determined to be inthe first mode in step 604, current from each battery unit is configuredto flow in accordance with the set current limit for that battery unit.In an example, the controller 160 enables the one direction current flowdevice 172 and the current regulator 174 for each battery unit 102 (anddisables the Schottky circuit 110) to enable current flow to the load140.

At step 608, which is reached if the system load is determined to be inthe second mode in step 604, current from each battery unit isconfigured to flow in accordance with a reduced current level. In anexample, the controller 160 enables the Schottky circuit 110 for eachbattery unit 102 (and disables the one direction current flow device 172and the current regulator 174) to provide reduced current flow to theload 140.

It will be understood that the terms and expressions used herein havethe ordinary meaning as is accorded to such terms and expressions withrespect to their corresponding respective areas of inquiry and studyexcept where specific meanings have otherwise been set forth herein.Relational terms such as first and second and the like may be usedsolely to distinguish one entity or action from another withoutnecessarily requiring or implying any actual such relationship or orderbetween such entities or actions. The terms “comprises,” “comprising,”“includes,” “including,” or any other variation thereof, are intended tocover a non-exclusive inclusion, such that a process, method, article,or apparatus that comprises or includes a list of elements or steps doesnot include only those elements or steps but may include other elementsor steps not expressly listed or inherent to such process, method,article, or apparatus. An element preceded by “a” or “an” does not,without further constraints, preclude the existence of additionalidentical elements in the process, method, article, or apparatus thatcomprises the element.

Unless otherwise stated, any and all measurements, values, ratings,positions, magnitudes, sizes, and other specifications that are setforth in this specification, including in the claims that follow, areapproximate, not exact. Such amounts are intended to have a reasonablerange that is consistent with the functions to which they relate andwith what is customary in the art to which they pertain. For example,unless expressly stated otherwise, a parameter value or the like mayvary by as much as ±10% from the stated amount.

In addition, in the foregoing Detailed Description, it can be seen thatvarious features are grouped together in various examples for thepurpose of streamlining the disclosure. This method of disclosure is notto be interpreted as reflecting an intention that the claimed examplesrequire more features than are expressly recited in each claim. Rather,as the following claims reflect, the subject matter to be protected liesin less than all features of any single disclosed example. Thus, thefollowing claims are hereby incorporated into the Detailed Description,with each claim standing on its own as a separately claimed subjectmatter.

While the foregoing has described what are considered to be the bestmode and other examples, it is understood that various modifications maybe made therein and that the subject matter disclosed herein may beimplemented in various forms and examples, and that they may be appliedin numerous applications, only some of which have been described herein.It is intended by the following claims to claim any and allmodifications and variations that fall within the true scope of thepresent concepts.

What is claimed is:
 1. A power source for delivering power to a systemload, the power source comprising: a plurality of battery units; aplurality of power flow devices coupled to the plurality of batteryunits and configured to provided power from the plurality of batteryunits to the system load when connected, each power flow devicecorresponding to a respective one of the plurality of battery units,each power flow device including a one direction current flow deviceconnected in series with a current regulator between the respectivebattery unit and the system load when connected; and a controllercoupled to the plurality of power flow devices and the plurality ofbattery units, the controller configured to set a respective currentlimit to a respective initial value for each of a plurality of batteryunits, monitor a system voltage level of the system load andindividually adjust the respective current limit of at least two of theplurality of battery units based on the monitored system voltage level.2. The power source of claim 1, wherein to individually adjust therespective current limit of at least two of the plurality of batteryunits the controller is configured to: increase the respective currentlimit of at least two of the plurality of battery units based on thesystem voltage level falling below a threshold voltage level.
 3. Thepower source of claim 2, wherein the threshold voltage level is aminimum voltage to activate the system load.
 4. The power source ofclaim 2, wherein the threshold voltage level is a minimum voltage tomaintain activation of the system load.
 5. The power source of claim 1,wherein: the one direction current flow devices of the plurality ofpower flow devices are configured to prevent current from flowingbetween the plurality of battery units; and the current regulator ofeach power flow device is configured to prevent the respective batteryunit from exceeding a rated current of the respective battery unit. 6.The power source of claim 1, wherein the respective current limit of thecurrent regulator of at least two of the plurality of current regulatorsis different.
 7. The power source of claim 1, each of the plurality ofpower flow devices further comprising: a respective Schottky circuitcoupled in parallel with the respective one direction current flowdevice connected in series with the respective current regulator.
 8. Thepower source of claim 1, wherein the respective current regulator is acurrent regulating load switch device comprising: a current sensingamplifier configured to sense current flowing through a currentregulating load switch device from the battery unit to the system loadwhen connected; a current regulator configured to regulate currentpassing from the respective battery unit to the system load whenconnected; and a current controller coupled to the current sensingamplifier and the current regulator, the current controller configuredto monitor sensed current and adjust the current regulator to maintainthe current at a set value.
 9. The power source of claim 1, furthercomprising: a plurality of chargers, each charger associated with arespective one of the plurality of battery units.
 10. The power sourceof claim 1, further comprising: a plurality of battery state determiningdevices, each battery state determining device associated with arespective one of the battery units and configured to determine a stateof charge of the respective battery unit; wherein the controller iscoupled to the plurality of battery state determining devices and to theplurality of power flow devices and is configured to adjust currentoutput of each of the plurality of battery units based on the state ofcharge of the plurality of battery units.
 11. Eyewear comprising: asystem load; a power source comprising: a plurality of battery units; aplurality of power flow devices coupled to the plurality of batteryunits and configured to provided power from the plurality of batteryunits to the system load, each power flow device corresponding to arespective one of the plurality of battery units, each power flow deviceincluding a one direction current flow device connected in series with acurrent regulator between the respective battery unit and the systemload when connected; and a controller coupled to the plurality of powerflow devices and the plurality of battery units, the controllerconfigured to set a respective current limit to a respective initialvalue for each of a plurality of battery units, monitor a system voltagelevel of the system load and individually adjust the respective currentlimit of at least two of the plurality of battery units based on themonitored system voltage; and a support structure configured to supportthe controller, the system load, and the power source.
 12. The eyewearof claim 11, wherein to individually adjust the respective current limitof at least two of the plurality of battery units the controller isconfigured to: increase the respective current limit of at least two ofthe plurality of battery units based on the system voltage level fallingbelow a threshold voltage level.
 13. The eyewear of claim 12, whereinthe threshold voltage level is a minimum voltage to activate the systemload.
 14. The eyewear of claim 12, wherein the threshold voltage levelis a minimum voltage to maintain activation of the system load.
 15. Theeyewear of claim 11, wherein the support structure includes a framehaving a first side and a second side and wherein the plurality ofbattery units includes a first battery unit positioned on a first sideof the frame and a second battery unit positioned on a second side ofthe frame.
 16. The eyewear of claim 11, wherein: the one directioncurrent flow devices of the plurality of power flow devices areconfigured to prevent current from flowing between the plurality ofbattery units; and the current regulator of each power flow device isconfigured to prevent the respective battery unit from exceeding a ratedcurrent of the respective battery unit.
 17. A power supply regulationmethod for supplying power to a system load, the method comprising:setting a respective current limit to a respective initial value foreach of a plurality of battery units, each of the plurality of batteryunits including a one direction current flow device connected in serieswith a current regulator between the respective battery unit and asystem load; monitoring a system voltage level of the system load; andindividually adjusting the respective current limit of at least two ofthe plurality of battery units based on the system voltage level. 18.The method of claim 17, wherein individually adjusting the respectivecurrent limit of at least two of the plurality of battery units based onthe system voltage level comprises: increasing the respective currentlimit of at least two of the plurality of battery units based on thesystem voltage level falling below a threshold voltage level.
 19. Themethod of claim 18, wherein the threshold voltage level is a minimumvoltage to activate the system load.
 20. The method of claim 18, whereinthe threshold voltage level is a minimum voltage to maintain activationof the system load.